Lawful Interception and Data Retention of communications can be made based on knowledge of the identity of a party responsible for transmitting or receiving the communication. For example if a mobile telephone number of a criminal suspect is known, it is possible to intercept or retain electronic communication sent from or received by the criminal suspect's mobile telephone. In governments around the world, various law enforcement agencies may have the right to authorize this interception/retention in their respective jurisdictions.
FIG. 1A is part of the prior art and discloses an Intercept Mediation and Delivery Unit IMDU, also called Intercept Unit. The IMDU is a solution for monitoring of Interception Related Information IRI and Content of Communication CC for the same target. The different parts used for interception are disclosed in current Lawful Interception standards (see 3GPP TS 33.108 and 3GPP TS 33.107-Release 7). A Law Enforcement Monitoring Facility LEMF is connected to three Mediation Functions MF, MF2 and MF3 respectively for ADMF, DF2, DF3 i.e. an Administration Function ADMF and two Delivery Functions DF2 and DF3. The Administration Function and the Delivery Functions are each one connected to the LEMF via standardized handover interfaces HI1-HI3, and connected via interfaces X1-X3 to an Intercepting Control Element ICE in a telecommunication system. Together with the delivery functions, the ADMF is used to hide from ICEs that there might be multiple activations by different Law Enforcement Agencies. Messages REQ sent from LEMF to ADMF via HI1 and from the ADMF to the network via the X1_1 interface comprise identities of a target that is to be monitored. The Delivery Function DF2 receives Intercept Related Information IRI from the network via the X2 interface. DF2 is used to distribute the IRI to relevant Law Enforcement Agencies LEAs via the HI2 interface. The Delivery Function DF3 receives Content of Communication CC, i.e. speech and data, on X3 from the ICE. Requests are also sent from the ADMF to the Mediation Function MF2 in the DF2 on an interface X1_2 and to the Mediation Function MF3 in the DF3 on an interface X1_3. The requests sent on X1_3 are used for activation of Content of Communication, and to specify detailed handling options for intercepted CC. In Circuit Switching, DF3 is responsible for call control signaling and bearer transport for an intercepted product. Intercept Related Information IRI, received by DF2 is triggered by Events that in Circuit Switching domain are either call related or non-call related. In Packet Switching domain the events are session related or session unrelated. In Packet Switching domain the events are session related or session unrelated.
While Lawful Interception is a real-time exercise, data from the past is used when Data Retention is practiced. FIG. 1B belongs to the prior art and shows the Handover Interfaces between a Data Retention System DRS (see ETSI DTS/LI-00033 V0.8.1 and ETSI DTS/LI-0039) at a Communication Service Provider CSP, and a Requesting Authority RA. The figure shows an Administration Function AdmF used to handle and forward requests from/to the RA. A Mediation and Delivery function MF/DF is used to mediate and deliver requested information. Storage is used to collect and retain all possible data from external the data bases. The generic Handover Interface adopts a two port structure such that administrative request/response information and Retained Data Information are logically separated. The Handover Interface port 1 HIA transports various kinds of administrative, request and response information from/to the Requesting Authority and the organization at the CSP which is responsible for Retained Data matters. The HIA interface may be crossing borders between countries. This possibility is subject to corresponding national law and/or international agreements. The Handover Interface port 2 HIB transports the retained data information from the CSP, to the Requesting Authority. The individual retained data parameters have to be sent to the Requesting Authority at least once of available). The HIB interface may be crossing borders between countries. This possibility is subject to corresponding national law and/or international agreements.
Lawful Interception and Data Retention needs specific target information to be activated on a suspect. Law Enforcement Authorities receive the mandate to intercept a certain person usually from a judge. Their first task is to discover the target identities that they can use to activate LI. If the user has a subscription with a telecom operator it is rather straightforward to ask the operator for this information and then activate the interception on the discovered identities. Valid for both Lawful Interception and Data Retention is that in most cases criminals try to keep their “identities” secret by for example using prepaid anonymous subscriptions to mobile networks, possibly buying the SIM cards abroad in countries where it is not mandatory to disclose own identity to buy a prepaid SIM or by using SIMS registered to someone else. The problem at hand is thus how to discover efficiently the target identities of a well known person subject of lawful interception and or data retention due to a judicial warrant.